C.E. Evans wrote:
Both the producers and the studio felt that the character wasn't working. When the character of Seven of Nine was conceived, there was already a sentiment by the studio that there were too many characters on the show as it was (i.e., they needed to trim the budget) and so someone had to go.
In other words, Jennifer Lien didn't feature enough boob and wasn't ready to wear skintight catsuits.
Actually, it was a case the producers felt the character had run out of steam. Her relationship with Neelix seemed like a good idea in the beginning, but then less so as the series progressed (it was why they started to have her in more scenes with other characters like the Doctor and Tuvok). The initial idea was to have both
Seven and Kes on the show, but the studio said no to having ten regular cast members.